Am I crazy?

Have you ever wondered if there is an exact replica of you somewhere in the world? Or if you have an "evil twin" in some alternate universe? Well I do, kind of, I don't really know.
While vacationing with my family in Florida a few years back, we decided to go souvenir shopping at a few boutiques near the pier. I ended up wandering off on my own into a few stores and found myself in some thrift store located a block away from the pier. While rummaging through a box of nick-knacks, I felt a strange vibe like someone had been watching me. So I began to search around the store to see if someone else was there, but it was just the cashier (who was watching a baseball game on a small television he had behind the counter) and I. Feeling a little creeped out because the vibe still lingered inside of me, I scurried out of the store; only to realize where the strange vibe originated from. Across the street stood my older brother Jacob, or at least I thought was my brother, staring straight at me. I thought maybe he was looking for me and it was time to leave; and the vibe, well I couldn't explain that. I waited until traffic cleared and ran across the street to meet up with my brother. When I reached the spot my brother stood, no one was there. I searched the busy sidewalk for him but he was nowhere to be seen. So I wandered back to the pier where my family had been shopping and found them sitting at an ice cream parlor. Joining them, I punched my brother in the arm and asked him why he didn't wait for me over at the thrift store. Now imagine yourself in math class and the teacher suddenly asks you for the answer to the problem on the board, and you blurt out Benjamin Franklin; now you see all those confused expressions of your surrounding classmates and teacher? Well I got those looks from my family, especially the "what the heck are you talking about" look from my brother. After explaining to them what had just happened to me minutes before, the overly confused looks turned into concerns. Lets just say I was completely freaked out for the remainder of our vacation and my family thought I was crazy.
Now I promise you, that super long short-story(get the irony?) has a point to it. When we returned from vacation, I did some research to prove I'm not completely crazy; because there are people out there that has faced the same situation as me. This supposedly "double" of my brother is called a "Doppelganger", which is German for "double-walker". A doppleganger is said to be a physical double of someone or even a evil twin. Two Jacob's? One of him is bad enough, and now the world wants to throw two at me. Maybe I am crazy, who knows.
This is where my blog comes into play. I'll be researching more in depth on what a doppleganger really is. If "they" are real or just an urban legend, because I myself am still a little iffy about it. Also I report some of the stories I read about online. Maybe this will decide whether I saw a doppelganger of my brother or I just mistaken the look of some stranger from a far distance.